createBatchSubscription.js

class NostrEvent extends Event {
  constructor(event) {
    super('event');
    this.event = event;
  }
}

const createBatchSubscription = () => {
  let timer = null;
  let filters = [];

  const exec = () => {
    const currentFilters = filters;
    filters = [];

    const mergedFilter = mergeFilters(currentFilters.map(({ filter }) => filter));

    const sub = pool.sub(relays, mergedFilter);
    sub.on('event', (event) => {
      currentFilters.forEach(({ filter, eventTarget }) => {
        if (matchFilter(filter, event)) {
          eventTarget.dispatchEvent(new NostrEvent(event));
        }
      });
    });
  };

  const sub = (filter) => {
    const eventTarget = new EventTarget();
    filters.push({ filter, eventTarget });

    if (timer == null) {
      setTimeout(() => {
        timer = null;
        exec();
      }, 3000);
    }

    return eventTarget;
  };

  return sub;
};

const subEvent = createBatchSubscription();
export const getEvent = (eventId) => subEvent({ kinds: [1], ids: [eventId] });

const subReposts = createBatchSubscription();
export const getReposts = (eventId) => subReposts({ kinds: [6], '#e': [eventId] });

const subReactions = createBatchSubscription();
export const getReactions = (eventId) => subReactions({ kinds: [7], '#e': [eventId] });